Can CT Histogram Analysis Predict the World Health Organization Grade of Rectal Neuroendocrine Tumors?

Abstract

Background: It is essential to discriminate low-grade (G1), intermediate-grade (G2) and high-grade (G3) rectal neuroendocrine tumors (R-NETs) due to the treatment decisions and postoperative management are totally different. CT histogram analysis, which is a novel method to provide objectively quantified assessment of tumor, may be helpful for differentiating the grade of R-NETs. Methods: A total of 61 (35 G1, 12 G2 and 14 G3) patients who underwent preoperative contrast-enhanced CT and treated with surgery to be confirmed as R-NETs were included in this study from January 2014 and May 2019. We accurately depicted the region of interest (ROI) and measured the CT texture parameters (mean, median, 10th, 25th, 75th, 90th percentiles, skewness, kurtosis and entropy) from arterial phase image by two radiologists. We calculated and compared these parameters between low-grade (G1), intermediate-grade (G2) and high-grade (G3) tumors by applying appropriate statistical method. We obtained the optimal parameters to identify G1 and G2/G3 by using receiver operating characteristic (ROC) curves. Findings: Histogram analysis of CT arterial phase imaging demonstrated significant differences between G1 and G2 or G3 group in several histogram parameters (mean, median, 10th, 25th, 75th and 90th percentiles) (all P 0.05). Skewness, kurtosis and entropy showed no significant differences among three groups ( P =0.449, 0.285, 0.057, respectively). ROC analysis showed a good predictive performance between G1 and G2/G3 and the mean generated the highest area under the curve (AUC = 0.832), followed by the median (AUC = 0.827). Interpretation: CT histogram parameters, especially mean and median, can be used as excellent indicators for predicting the grade (G1 and G2/G3) of rectal neuroendocrine tumors. Funding Statement: This study has received funding by the National Natural Science Foundation of China (Grant No.81771801,81801695, 81701657 and 81873623). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The Institutional Review Board of our hospital (Medical Ethics Committee of Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology) approved this retrospective study and the requirement for patient informed consent was waived.